There is no question that the ability to see clearly is a most treasured and valued human ability. Regrettably, many vision disorders commonly exist. Focusing disorders such as near-sightedness (myopia), far-sightedness (hyperopia) and astigmatism are very common and are normally treated with prescription lenses (eyeglasses or contact lenses) or refractive surgery. Disorders of the muscles that steer the eyeballs and eye alignment disorders such as strabismus and diplopia are also widespread. And finally, retinal disorders such as macular degeneration, diabetic retinopathy and glaucoma affect tens of millions of persons in the U.S. alone.
Given the broad number of vision conditions that affect the population, it is naturally important that measurement and screening capability be available. Of course, a very large number of optometrists and ophthalmologists perform vision screening and diagnosis on a daily basis. These screening and measurement procedures are normally performed in a specialist's office and often include complex and expensive vision measurement instruments and time consuming interaction between the care provider and the patient. Even once they are diagnosed and treated, some vision diseases such as macular degeneration, diabetic retinopathy and glaucoma require ongoing monitoring that demands repeated visits to a specialist to ensure the disease is remaining under control. Consequently, vision measurement and screening systems that reduce cost, improve accuracy, improve convenience for the care provider or the patient or improve vision measurement and screening ability in other ways are highly beneficial. And as noted, since certain eye diseases require ongoing monitoring, automatic systems that can store measurement data, compare it with new measurements and alert patients or care providers if substantial changes have occurred are also highly desirable and beneficial.
While the need for high quality vision measurement and screening systems is very well established and accepted, vision training has been a topic of controversy. Vision training, vision therapy, eye exercise, vision exercise, orthoptics and some other terms have been used as names for techniques that use training techniques to improve vision function through either training of the eye itself, or by training the brain to improve its interpretation of nerve signals from the eye. In this discussion, “vision training” will normally be used to refer to these techniques, but any of the names listed above can be used to refer to them. In the past, some of these therapies have made claims of “miracle cures” for eye disease and, in some cases, no scientific basis or proof of effectiveness has been available. This has lead some to believe that vision training is not effective. However, vision training has been found to be effective when applied appropriately and for appropriate patient conditions under a professional care provider's supervision.
In 1999 the American Academy of Optometry and the American Optometric Association issued a joint policy statement on vision therapy. This statement can be found in its entirety at the American Academy of Optometry website at www.aaopt.org, so it will not be repeated here. However, several excerpts are very enlightening. The policy statement states: “The human visual system is complex . . . . Many visual conditions can be treated effectively with spectacles or contact lenses alone; however, some are most effectively treated with vision therapy. Vision therapy is a sequence of activities individually prescribed and monitored by the doctor to develop efficient visual skills and processing . . . . The use of lens, prisms, filters, occluders, specialized instruments and computer programs is an integral part of vision therapy.” And finally, it is noted that the policy statement states that “Research has demonstrated vision therapy can be an effective treatment for:                Ocular motility dysfunctions (eye movement disorders),        Non-strabismic binocular disorders (inefficient eye teaming),        Strabismus (misalignment of the eyes),        Amblyopia (poorly developed vision),        Accommodative disorders (focusing problems), and        Visual information processing disorders, including visual-motor integration and integration with other sensory modalities.”        
This joint policy statement on vision therapy makes it very clear that vision therapy or training techniques are effective when properly prescribed for patients with conditions appropriate for a specific therapy. Indeed, vision training has become more widely accepted in recent years. The FDA (Food and Drug Administration) has approved a vision training regimen offered by Neurovision Incorporated for the treatment of amblyopia (www.neuro-vision.com). The American Optometric Association website at www.aoa.org explains the use of prisms in the treatment of strabismus and discusses ways to use vision training in treatment of other vision disorders as well. The effectiveness of fixation training (also sometimes called parafovea training or off-foveal training) which is sometimes used to help patients suffering from macular degeneration learn to make the best use of their remaining vision function is also well established (www.aoa.org/documents/CPG-14.pdf provides a summary of treatments for low vision including teaching off-foveal viewing with guided practice techniques).
Hence, it is well established that vision training techniques are effective when appropriate training regimens are prescribed for certain vision disorders. As would be expected, there have been some attempts to produce devices and therapies to provide vision training. Liberman, for example, U.S. Pat. No. 6,742,892 teaches a device with lights at various distances from a user to improve focusing ability. Regrettably, such devices are somewhat cumbersome, have limited or no ability to measure vision function and are rather boring to operate making it difficult to fully engage a patient in the training regimen. This last issue is especially problematic for use with children. Mateik teaches a binocular viewer in U.S. Pat. No. 4,756,305 that includes the ability to interchange prisms and lens to allow for vision training for strabismus treatment and other treatments as well. Regrettably, Mateik's device cannot measure a patient's vision performance nor adapt automatically to create an effective training system. As the lenses are fixed for a given training session, only limited ranges and accommodations are possible. Hence, it is clear that vision training devices that offer improvements over prior art are highly desirable.
Fortunately, computer graphics and gaming technology has now advanced to the level that low cost, highly effective devices for vision diagnosis, tracking and training can be envisioned. Binocular viewers allow each eye to be measured or trained independently or together, advances in variable optics allow for changes in focus to be accommodated, computer generated graphics allow interesting and engaging images to be created and low cost human input devices allow user feedback information to be collected easily concerning how a user is reacting to a given image or sequence of video.